21120221220 has 96 divisors (see below), whose sum is σ = 68859963648. Its totient is φ = 4736389632.

The previous prime is 21120221219. The next prime is 21120221257. The reversal of 21120221220 is 2212202112.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21120221220.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 452139 + ... + 496658.

It is an arithmetic number, because the mean of its divisors is an integer number (717291288).

Almost surely, 2^21120221220 is an apocalyptic number.

21120221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21120221220 is an abundant number, since it is smaller than the sum of its proper divisors (47739742428).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21120221220 is a wasteful number, since it uses less digits than its factorization.

21120221220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 948869 (or 948867 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21120221220 its reverse (2212202112), we get a palindrome (23332423332).

The spelling of 21120221220 in words is "twenty-one billion, one hundred twenty million, two hundred twenty-one thousand, two hundred twenty".